Spring of nickel iron alloy



Patented Mar. 2, 1937 PATENT OFFICE SPRING OF NICKEL IRON ALLOY Reinhard Straumann,

Waldenburg, Canton of Bale-Campagne, Switzerland No Drawing.

Serial No. 109,059. 13, 1935 2 Claims.

A nickel iron alloy for the springs of thermocompensated oscillating systems, for example balance springs for clocks and watches, is known which by additions of metals of the chromium group exactly proportioned in relation to one another and to the nickel content, yields a hard, highly elastic spring which has a thermo-elastic coefllcient which is zero, positive or negative according to the choice and proportion of the addition and which can be fixed in shape in a satisfactory manner at the refining temperature.

Manufacturing experience has shown that these alloys of the above composition have certain disadvantages.

(l) The thermo-elastic coeflicient depends very greatly on the fixing temperature and therefore requires extreme precision in the heat treatment, which at the relatively high fixing temperature of above 600 C. up to over 700 C. involves some difllculties.

(2) It has hitherto been impossible to make springs with chromium-beryllium additions which can be satisfactorily fixed in the desired form during refining heat treatment.

(3) The secondary error of the thermo-elastic coefficient is also reatly dependent on the fixing temperature; this dependence at the present time amounts to up to 5 seconds for each degree centigrade variation in the fixing temperature.

3 It has now been found possible by the combination of additions of tungsten and beryllium, molybdenum and beryllium or chromium and beryllium with titanium to obtain nickel iron alloys in springs which not only have the advantages of the known alloys, but also the suppression of the above mentioned disadvantages and afford the additional new advantage that the fixing temperatures of the springs can be kept lower. The addition of titanium to beryllium and one of the metals selected from the group consistin of chromium, molybdenum and tungsten in a nickel iron alloy with a nickel content of 25-40% results in the following novel features.

(1) An approximately 5 fold reduction in the 5 dependence of the thermo-elastic coefllcient and its secondary error on the fixing temperature. This now amounts to 0.5-1 second for each de- Application November 3, 1936,

In Germany December lst example 2nd example 3rd example 30-38% Ni. 30-387 Ni.

Remainder Fe.

Remainder Fe Obviously, two or all three of the alloying metals of the group consisting of chromium, molybdenum and tungsten can also be present together or simultaneously in the alloy, always provided that their total content amounts from 5 to 12% of the alloy.

What I claim is:-

l. A nickel iron alloy with a hardening addition of beryllium, for the springs of thermo-compensated oscillating systems, for example balance springs for clocks and watches, in which with a content of 25-40% of nickel and 0.5-2% of beryllium with a calculated quantity of alloying addition of at least one of the metals of the group consisting of molybdenum, chromium and tungsten amounting to a total content of 542%, 0.5-2% of titanium is also alloyed, with the object that in addition to the great hardness achieved and the low temperature coemcient, the dependence of the latter and its secondary error on the fixing temperature is greatly reduced to the rate of 0.5-1 second for each degree centigrade variation of the fixing temperature.

2. A spring made of an alloy according to claim 1.

REINHARD STRAUMANN. 

